Answer:
The width and length of rectangle is 12.728 m
Step-by-step explanation:
Let the length of the rectangle = L
let the width of the rectangle = W
The subjective function is given by;
F(p) = 2(L + W)
F = 2L + 2W
Area of the rectangle is given by;
A = LW
LW = 162 ft²
L = 162 / W
Substitute in the value of L into subjective function;
[tex]f = 2l + 2w\\\\f = 2(\frac{162}{w} )+2w\\\\f = \frac{324}{w} + 2w\\\\\frac{df}{dw} = \frac{-324}{w^2} +2\\\\[/tex]
Take the second derivative of the function, to check if it will given a minimum perimeter
[tex]\frac{d^2f}{dw^2}= \frac{648}{w^3} \\\\Thus, \frac{d^2f}{dw^2}>0, \ since,\frac{648}{w^3} >0 \ (minimum \ function \ verified)[/tex]
Determine the critical points of the first derivative;
df/dw = 0
[tex]\frac{-324}{w^2} +2 = 0\\\\-324 + 2w^2=0\\\\2w^2 = 324\\\\w^2 = \frac{324}{2} \\\\w^2 = 162\\\\w= \sqrt{162}\\\\w = 12.728 \ m[/tex]
L = 162 / 12.728
L = 12.728 m
Therefore, the width and length of rectangle is 12.728 m
